NYTimes | Those who make the Very Large Mistake (of thinking they know enough about the nature of the physical to know that consciousness can’t be physical) tend to split into two groups. Members of the first group remain unshaken in their belief that consciousness exists, and conclude that there must be some sort of nonphysical stuff: They tend to become “dualists.” Members of the second group, passionately committed to the idea that everything is physical, make the most extraordinary move that has ever been made in the history of human thought. They deny the existence of consciousness: They become “eliminativists.”
This amazing phenomenon (the denial of the existence of consciousness) is a subject for another time. The present point — it’s worth repeating many times — is that no one has to react in either of these ways. All they have to do is grasp the fundamental respect in which we don’t know the intrinsic nature of physical stuff in spite of all that physics tells us. In particular, we don’t know anything about the physical that gives us good reason to think that consciousness can’t be wholly physical. It’s worth adding that one can fully accept this even if one is unwilling to agree with Russell that in having conscious experience we thereby know something about the intrinsic nature of physical reality.
So the hard problem is the problem of matter (physical stuff in general). If physics made any claim that couldn’t be squared with the fact that our conscious experience is brain activity, then I believe that claim would be false. But physics doesn’t do any such thing. It’s not the physics picture of matter that’s the problem; it’s the ordinary everyday picture of matter. It’s ironic that the people who are most likely to doubt or deny the existence of consciousness (on the ground that everything is physical, and that consciousness can’t possibly be physical) are also those who are most insistent on the primacy of science, because it is precisely science that makes the key point shine most brightly: the point that there is a fundamental respect in which ultimate intrinsic nature of the stuff of the universe is unknown to us — except insofar as it is consciousness.